EPT[Guide] Solving The Rubik's Cube - Page 6
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ODKStevez
Ireland1225 Posts
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micronesia
United States24745 Posts
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oDieN[Siege]
United States2905 Posts
On October 10 2011 07:37 micronesia wrote: The first two algorithms (white cross then white corners) are easy to visualize and understand what's happening. They don't need to be magic... you can figure them out yourself. I just haven't gotten that same vibe from solving the second or third layer at all... I'm just using the algorithms given to me (which were a bitch to memorize hahaha) Haha, yeah I agree. It took me like 3 days to memorize the algorithms. I'm still not quite sure how people can honestly solve a rubiks cube in 30 seconds. My fastest time is 1 minute 47 seconds. | ||
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ooveehoo
Finland13 Posts
On October 10 2011 07:37 micronesia wrote: The first two algorithms (white cross then white corners) are easy to visualize and understand what's happening. They don't need to be magic... you can figure them out yourself. I just haven't gotten that same vibe from solving the second or third layer at all... I'm just using the algorithms given to me (which were a bitch to memorize hahaha) I don't really get the thing about just memorizing algorithms to solve the first time. For getting faster, learning move sequences by heart is necessary (I know this for having competed in speedcubing for almost five years). But I recommend trying to solve the cube by yourself the first time around, it's just such a feeling to have solved the bloody thing after hours and hours of hard studying, desperation and anger. Nice to see that there are speedcubers here too. And great post by OP. | ||
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JeeJee
Canada5652 Posts
On October 10 2011 07:37 micronesia wrote: The first two algorithms (white cross then white corners) are easy to visualize and understand what's happening. They don't need to be magic... you can figure them out yourself. I just haven't gotten that same vibe from solving the second or third layer at all... I'm just using the algorithms given to me (which were a bitch to memorize hahaha) You're referring to the 2nd layer algs listed in the OP right? The D'F'DFDLD'L' and its mirror? I suppose I can try and explain the intuition behind what you're doing there. This is for the left case, it's the same for the right case, simply mirrored. I'll use the colours/pictures from the OP tutorial so you can refer to them. Basically you're trying to put the edge piece into its slot (so the blue-orange piece between blue and orange centers) without affecting anything else in the first two layers. That's impossible without messing them up a bit first -- so this algorithm has two steps 1) Take out the blue-orange-white corner and put it beside the blue-orange edge so that they're joined together. I'm going to call this a "pair" or "paired" pieces 2) Put the corner-edge pair back where it came from When trying to follow the below explanation, trace the corner and edge as they move, so it'll all make sense (hopefully) In terms of the actual moves, this is how it works: D' relocates the edge piece so that when you take out the corner, it's automatically put into the right place. This'll make more sense in a sec. F'DF takes out the corner, and if you'll look carefully, you'll notice it's right beside the edge piece! That was the purpose of the D' originally. If you didn't do the D', the corner piece would be beside a different edge piece. This completes step (1) above Now we have to put this pair back where it came from. Actually what you're doing here is the same way you put the corners in. If you think about it, you already put the corner in while doing the first layer, except it was paired with the wrong edge piece. So to put the corner in, you do D to align LD'L' to slide in the corner-edge pair. At the cost of redundancy, you get a much simpler method. If you think about it, what you're doing is basically -cross -put in the corners with wrong edge -take out the corners, match them up with right edge -put them back in You can combine and pair the corner-edge pairs right away, as you get more advanced. Hope this provides some intuitive explanation for the algorithms in the op! e: Explanations are never my strength so apologies if this doesn't make any sense. Let me know if I can clear some parts up.. | ||
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Carras
Argentina860 Posts
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Diglett
600 Posts
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RogerX
New Zealand3180 Posts
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JeanBob
Canada295 Posts
On October 10 2011 10:53 Diglett wrote: is speedcubing still popular? it was very popular in high school but i don't see anyone with them in college :[[ Doesn't matter that much, I made it popular in my own high school back then. It was funny, I borrowed it from a friend, took it to school, on the first few days I was no clue about how to solve it, then checked on the internet, then everyone was soooo impressed, many people bought their own cubes after. Quickly looking through this guide: I wish I found that back then when I learned how to solve rubik's cube. I'm trying to learn all of Fridrich's method, but I'm getting really lazy and stopped after F2Ls, so I average something around 35 seconds. | ||
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Orpheos
United States1663 Posts
On October 10 2011 10:55 RogerX wrote: I cheat, I take the stickers off and stick them back on so it looks like I completed it ): I love how people do this because there is a MUCH easier way. you can just take the whole cube apart and put it back together. the mechanism is not exactly the most perplexing thing. Id be especially amused if people took off the center stickers. | ||
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ClysmiC
United States2192 Posts
On October 10 2011 10:55 RogerX wrote: I cheat, I take the stickers off and stick them back on so it looks like I completed it ): That still takes longer than the rate that some people can legitimately solve it at D: | ||
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FinestHour
United States18466 Posts
I still failed miserably. | ||
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[Agony]x90
United States853 Posts
On October 10 2011 11:37 ClysmiC wrote: That still takes longer than the rate that some people can legitimately solve it at D: Not many things can be done under 10 seconds in terms of cheating the rubik's cube. Maybe if you took 6 paint brushes and brushed all 6 sides simultaneously you might be able to beat the world record. lol. | ||
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XXGeneration
United States625 Posts
On October 10 2011 11:40 [Agony]x90 wrote: Not many things can be done under 10 seconds in terms of cheating the rubik's cube. Maybe if you took 6 paint brushes and brushed all 6 sides simultaneously you might be able to beat the world record. lol. My personal best is 10.xx seconds, and I average 14.xx seconds. I have been speedcubing for maybe a year though. | ||
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JeanBob
Canada295 Posts
On October 10 2011 07:39 ODieN wrote: Haha, yeah I agree. It took me like 3 days to memorize the algorithms. I'm still not quite sure how people can honestly solve a rubiks cube in 30 seconds. My fastest time is 1 minute 47 seconds. We just memorized more algorithms, learned finger tricks and practiced a looooooot. | ||
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mmp
United States2130 Posts
My strategy is to get the corners in correct place first (as though you were solving a 2x2x2 cube), and then use algorithms that preserve corners to rearrange the sides. I like that it doesn't require a layer-by-layer approach and I can focus on any area that I want provided that the corners remain intact, and it's generally easy to reestablish corners if I ever experiment too far. The only problem is that I haven't formalized a lot of the corner-preserving algorithms, and sometimes you will try one to achieve something, but with unknown side-effects for other sides. Fortunately the side effects are minimal, such that I was able to pretty easily direct everything down to a near-complete state. Here's the state: + Show Spoiler +
So there are three sides YR, BY, and RB that need to be swapped. The other 3 faces are complete. Any ideas what algorithm can rotate these 3 pieces without affecting any others? | ||
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AnachronisticAnarchy
United States2957 Posts
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JeeJee
Canada5652 Posts
On October 10 2011 12:29 mmp wrote: I've been working on a 3x3x3 cube using a different strategy than the ones in the OP, and I'm really really close to complete (I think). Maybe you guys can help me finish. My strategy is to get the corners in correct place first (as though you were solving a 2x2x2 cube), and then use algorithms that preserve corners to rearrange the sides. I like that it doesn't require a layer-by-layer approach and I can focus on any area that I want provided that the corners remain intact, and it's generally easy to reestablish corners if I ever experiment too far. The only problem is that I haven't formalized a lot of the corner-preserving algorithms, and sometimes you will try one to achieve something, but with unknown side-effects for other sides. Fortunately the side effects are minimal, such that I was able to pretty easily direct everything down to a near-complete state. Here's the state: + Show Spoiler +
So there are three sides YR, BY, and RB that need to be swapped. The other 3 faces are complete. Any ideas what algorithm can rotate these 3 pieces without affecting any others? Sure. I could run a solver and give you the optimal solution but that's boring. We should learn to create algorithms! Here's one approach Quick notation: F=front face, B=back, Left Right Up Down. If I say UL that means the U part of the Up-Left edge piece. So for your cube, if red's on the top and yellow's in front, UL would be red-blue (LU would be blue-red since that would be the left part of the up-left piece) Clear so far? So, let's assume red is on top. You wish to move pieces as follows (if I'm reading your drawing correctly): RU -> UF -> RF -> RU Notice how this forms a cycle. To solve a typical cycle like this, without going way too indepth (that would border on writing a full guide), we want two pieces in one interchangeable layer (basically where we can put one piece into the others' place with one move), and the third piece somewhere else. We already have this here, since RU and RF are on the same layer and are easily swapped with R or R' So all we need to do is move the UF piece somewhere more useful so we can move it around without affecting the other two pieces. I'll call this setup moves, since they set up the solution. We can do this with M2 D To make it easier to visualize from now on, let's do a quick rotation (f') So now, we simply have to insert that piece into the R layer without messing up any other piece in that layer (we can mess up everything outside of that layer because we'll undo it later) We can do that with M' D' M Now we swap it with the other piece U' and undo our insertion M'DM Now we undo the swap U and now we undo the setup (remember we rotated so we undo that too!) (f) D' M2 So final alg: M2D (f') M' D'M U' M'DM U (f) D' M2 I did this in my head so my apologies if I made a mistake somewhere. e: Oh yeah, M follows R if that's an ambiguity. so M' is like R' but for M layer. e2: I found a cube and tested it, it worked! hurrah. | ||
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mmp
United States2130 Posts
On October 10 2011 12:54 JeeJee wrote: Sure. I could run a solver and give you the optimal solution but that's boring. We should learn to create algorithms! Here's one approach Quick notation: F=front face, B=back, Left Right Up Down. If I say UL that means the U part of the Up-Left edge piece. So for your cube, if red's on the top and yellow's in front, UL would be red-blue (LU would be blue-red since that would be the left part of the up-left piece) Clear so far? So, let's assume red is on top. You wish to move pieces as follows (if I'm reading your drawing correctly): RU -> UF -> RF -> RU Notice how this forms a cycle. To solve a typical cycle like this, without going way too indepth (that would border on writing a full guide), we want two pieces in one interchangeable layer (basically where we can put one piece into the others' place with one move), and the third piece somewhere else. We already have this here, since RU and RF are on the same layer and are easily swapped with R or R' So all we need to do is move the UF piece somewhere more useful so we can move it around without affecting the other two pieces. I'll call this setup moves, since they set up the solution. We can do this with M2 D To make it easier to visualize from now on, let's do a quick rotation (f') So now, we simply have to insert that piece into the R layer without messing up any other piece in that layer (we can mess up everything outside of that layer because we'll undo it later) We can do that with M' D' M Now we swap it with the other piece U' and undo our insertion M'DM Now we undo the swap U and now we undo the setup (remember we rotated so we undo that too!) (f) D' M2 So final alg: M2D (f') M' D'M U' M'DM U (f) D' M2 I did this in my head so my apologies if I made a mistake somewhere. e: Oh yeah, M follows R if that's an ambiguity. so M' is like R' but for M layer. e2: I found a cube and tested it, it worked! hurrah. I'll have to walk through this step-by-step, but thanks!  | ||
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JeeJee
Canada5652 Posts
On October 10 2011 13:38 mmp wrote: I'll have to walk through this step-by-step, but thanks! Sure no problem. And just for kicks, jacube tells me the optimal solution is FULDR F'R'D'L'U' And the most finger-friendly solution is R'F'R'F'R'F'RFRFR2 Or rotated so that F's become U's: (r) R'U' R'U' R'U' RU RU R2 (r') While way better than my alg, unfortunately I can't tell you why or how they work. Ah the mysteries of the cube.. | ||
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